Electrolytic precipitation of copper



msnm@ F. LAlsT ET AL ILECTROLYTIC PRECIPITATION OF COPPER Filed oon. 25, 1925 Crsed @me eaenfed Agr. 13, 192s.

TION OFQMONTANA.

l11s-nieu V- ELECTROLYTIC ERECIPITATION OF COPPER.

`Application led October 23, 1925. Serial No.

To cZZfw/iom t 'may concern:

Be it known that we, FREDERICK LAIs'r and Fiuannnicii States, residing F. Finali,

citizens of the United at Anaconda in the county of Deerlodge and State of Montana, have inf and other"impurities vented certain new an in the Electrolytic :P

ci' which the This invention relates leaching-electrol of copper from 'to a method of cially the iron,

copper ores the prises leaching the ore wi taining sulfuric plied for the recovery ytic process for the recover ores,

removing d useful Improvements reeipitation of. Copper, following is aspeciiication. to the so-called and more particularly' impurities, espefrom the -leaching solution. In leaching-electroyltic processes as apof copper from oxide customary 'procedure com'- tliis solution to electrolysis per is precipitated and combined .with

and using the resulting 's the regenerated more ore. cyclical.

In practice th ordinarily is not supplemented by othe care Ocertain c of these conditi/ i i n the Asolution (he ore,

pending u )on method of caching, ifa s The procedure,

th a solution conacid, thereby forming a sosulfate, subjecting whereby the copthe sulfuric acid the copper is regenerated,

l sulfuric olution containing acid for leaching as 1s apparent, 1S

e simple procedure outlined followed, but is modified or r steps designed to take onditions which arise. One

ons is the produced the ery of copper from the ore if the leaching of the ore complish a satisfactory re( Iron is a. most undesirable per-bearing solutions .from is to be recovered by electrolysis. In the electrolysis the at the anode and reducing the current eiciency.'

iron is reduced at presence of iron derived vfrom the ore by the leaching.

` livays dissolved from thereof of ro ore treated and the atisfactory recovurse deis made, that is, is such as to ac- ,ovcry of copper.

impurity in copwhich the coppi-r alternately oxidized the cathode, thus The iron also causes a corrosion'ot' the cathode, and besides the solution produced by the electrolysis and still eifective as a lution free of or be apparent in d lined, unless ste from the eyelids containing tl leaching solu low in iron the cyclical ieiron is far less tion than 1s a so-4 content. As will procedure outn to remove iron liquid it will become continuously more and more contamiy Irecovering the copper content thereof as ce- Y ment copper by precipitation with iron. This 1 method is `not satisfactory for several reasons, among which may be mentioned the cost of the" iron used and the undesirability of cement copper as compared with cathode copper. Moreover, the quantity of iron ordinarily tion, according to this method, reduces .the eiiciency of the leaching andpf the' electrolysis to an appreciable extent. It is necessary to make a compromise between the production of cement copper on'the one hand and the quantity of iron left'in the solution on the other hand, both the production of cement copper -and leaving iron in the solubeing undesirable. The harmful effect o iron in leaching-electrolytic process for the recovery of copper from ores is well known and is discussed in thecurrent literature. 1

7e have developed a satisfactory commercial process for the'emoval of iron land other solutions used in leaching-electrolytic processesof which the procedure described below is an illustrative example.

A. copper ore capable of yielding to 30 pounds of copper per ton is leached, preferably by'a counter-current procedure. About one-fourth of la pound ot iron and one- 'iing solution may contain, for example, 40 grams of copper, 7 to l0 grams of iron, 5 to 6 grams of aluminum and 10 grains of free sulfuric acid per liter. This solution is agitated with limerock in the form oi" particles preferably of less than (35 mesh in quantity amounting to 'about 30 grams of limerock per liter. of solution. Limerock isa natural limestone rock and may be regarded simply as an inexpensive supply of calcium car onate. The agitation of the solution with t e limerock results in left in ,the cyclically moving solu`` impurities associated therewith in the y precipitate containing basic iron and aluminum calcium sulfato which is tion and Washed. .llhis zitate contains substantiallT all of the ieric iron or about H 'l y i to 90 per cent ot the total u t half of the aluinintun and substantially all. of the phosphorus arsenic antimony present in the leaching solution treated. The purified solution containingI 'l1/6 to 21. crains cit'iron e. /l.. n i.. di l per liter 1s Well adapted Ior tnc eleetrolytic precipitation of its copper content. it gives a `bulky principally compounds and 7ated. by filtraa high yield of cathode copper and a regenercopper carbonate or ated sulfuric acid solution suitable for use directly for leaching a vturther quantity ot ore. The procedure described above is illustrated on the accompanying drawing which isya'li'oW-shcet of the process.

The precipitate produced by the limerock treatment of the leaching' solution ordinarily contains about 2 percent or less of the total quantity of copper dissolved from the ore. This' copper may bey recovered, if it is economically feasible, by methods not afpart of the present invention and Which'need not be described.

In vconnection v it 'isnoted that suitable changes in the speciiic rocedure.described'may be made. Without eparting from our invention. The procedure is applicable to any ore capable of being treated by the ,leaching-eleetrolytic process which contains impurities which would ,interfere with the continuous voperation ofthe process and which may-loe re moved by the l limerock precipitation. The

solutions referred to concentrations of the course are. merely illustrative and may be varied. rlhe quantity of lirncrock to be used will varywith the acidity and quantity of impurities present in the solution treated and may also be varied to suit-the degree of purification desired. The use of limerocl;

in sullicient quantity will cause a precipita' cont-ent Yof the solution as tion of lthe copper basic carbonate. in

which are with the foregoing example,-

4 trolysis, and using associa The quantityto be used in used is just snilicient to give a substantially #i5 neutral solution,

In place of limeroclr, any other suitable basic precipitan't, such as linie, may be used but we prefer to use limerock-.or limestone since it is etliective and inexpensive. Other modifications of `the cyclicalprocedure for other purposes, tor instance, the recovery of copper from the linierock precipitation, may of course be made without departing from our invention. A

1. In a process for the recovery of'c'opper from ores comprising leaching an ore Wit-h a` solution containing an acid, subjecting the leaching solution to electrolysis Vto'fpre'cipitate the copper,andcregenerate the acid and' usingtheregenerated acid for leaching more ore, the step which consists in treating said leaching solution With a reagent capable of precipitating iron. 4 i

In a process comprising leaching an oxide copper ore containing iron Withn` solution containing sulfuric acid, subjecting the resulting leaching solution to electo leach more oxide copper ore containing iron.. the step which consists in agitating said leaching solution prior to subjecting it to electrolysis with finely divided limerock esk the electrol'yzed solution 80 in quantity sufficient te precipitate.substan- 'B5 tially all et the Solution and separating the resulting pre# cipitate from the solution.

lintestiinony Whereoi", We allix our signatures.

FEEDER CK LAIST. FREDERICK F. FRICK.

ferrie iron present in the 

